Deterministic Generation of Four-Component Schrödinger Cat States via Floquet Engineering in a Hybrid Magnon-Superconductor System

Abstract: Four-component Schr\"odinger cat states, superpositions of four coherent states symmetrically arranged in phase space, offer rich nonclassical features and enhanced resilience to decoherence, making them promising resources for quantum information science. We propose a Floquet-engineered scheme to deterministically generate four-component Schr\"odinger cat states in a hybrid quantum system composed of two superconducting qubits, a microwave cavity, and a magnon mode. By applying periodic transverse drives to the qubits, we derive an effective Hamiltonian that conditionally displaces the magnon mode depending on the joint qubit state. Conditional measurements in the $\sigma_x$ basis project the magnon mode into nonclassical four-component cat states with high fidelity. The Wigner functions in the original frame verified the non-classicality of the four-component Schr\"odinger cat states. Results of systematically analyzing the impacts of qubit decoherence, magnon loss, and cavity dissipation demonstrate the robustness to the dissipation. The results show that this scheme can realize the generation of multi-component quantum superposition states in a scalable solid-state platform, providing a new approach for hybrid quantum information processing based on nonclassical magnon states.tates.